Herring scaling laws

As the average particle size in green compact is reduced, the specific surface area increases and the diffusion distance is reduced. Both effects produce higher densification rates. According to the Herring scaling law [22],... 

The values of m given above conform to Herring s scaling law (1950) which states that since the driving force for sintering, the transport length, the area over which transport occurs and the volume of matter to be transported are proportional to a 1, a, cr and a3 respectively, the times for equivalent change in two powder samples of initial particle size fl o and a2,o are... 

Table 5.3 Exponents for Herring s scaling laws described by Eq. (5.128)...

This equation indicates that the densification rate at a given density is dependent inversely on the cube of the grain size, which is in agreement with the prediction by the Herring s scaling law. 

The exponent a in the scaling law can also be deduced from the sintering equations in Table 4.2 without following Herring s derivation. The sintering... 

The scaling laws for the otho- mass transport mechanisms can be daived using a procedure similar to that outlined above for lattice diffusion, as described in detail by Herring (5). The laws can be written in the general form... 

Particle size is an important element in the performance of an HTCC system. Fine particle size enhances densification although submicron particles are often difficult to disperse effectively. A basic description of the effect of particle size on the sintering of particles is captured in Herring s scaling law that describes an exponential dependence of sintering time on particle diameter [21] ... 

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